feat(library): Steam wishlist tab with prices and discounts

The library page gets a Bibliothek | Wunschliste tab bar. The wishlist shows
the current store price, the discount and can show only games on sale.

src/components/LibraryTabs.jsx

@@ -0,0 +1,32 @@
+import {NavLink} from 'react-router-dom';
+import {useTranslation} from 'react-i18next';
+import {Gift, Library} from 'lucide-react';
+
+import {cn} from '@/lib/utils';
+
+const TABS = [
+    {to: '/library', labelKey: 'LIBRARY.TITLE', icon: Library},
+    {to: '/wishlist', labelKey: 'WISHLIST.TITLE', icon: Gift},
+];
+
+export default function LibraryTabs() {
+    const {t} = useTranslation();
+    return (
+        <nav aria-label={t('LIBRARY.TITLE')} className="inline-flex rounded-lg bg-muted p-1 text-sm">
+            {TABS.map(({to, labelKey, icon: Icon}) => (
+                <NavLink
+                    key={to}
+                    to={to}
+                    end
+                    className={({isActive}) => cn(
+                        'flex items-center gap-1.5 rounded-md px-3 py-1.5 font-medium transition-colors',
+                        isActive ? 'bg-background text-foreground shadow-sm' : 'text-muted-foreground hover:text-foreground',
+                    )}
+                >
+                    <Icon className="size-4"/>
+                    {t(labelKey)}
+                </NavLink>
+            ))}
+        </nav>
+    );
+}